One Health is an approach that recognizes the tight connections between human health, animal health and the environment, and uses those links to better understand, prevent and respond to disease. It is especially important for emerging infectious diseases, since many of them originate in animals before spreading to people.

Research in this field shows that a large proportion of new human diseases are zoonotic. Pathogens can jump between wildlife, livestock, companion animals and humans, often facilitated by land use change, intensive farming, wildlife trade and climate change. These drivers alter habitats, increase contact between species and shift the distributions of hosts and vectors.

Scientists working with a One Health lens combine tools from epidemiology, ecology, veterinary medicine, human medicine, microbiology and social sciences. They model how pathogens circulate in complex host communities, track transmission routes at the human animal interface and examine how environmental conditions shape outbreaks. This helps identify early warning signals and points of intervention.

Examples include integrating animal and human surveillance systems, using genomic sequencing to trace cross species transmission, and assessing how deforestation or urbanization modifies disease risk. Studies also evaluate how antimicrobial use in humans and animals fuels resistance that then spreads through the environment.

A key conclusion of this research is that controlling disease only in humans, or only in animals, is often ineffective. Coordinated policies across health, agriculture and environmental sectors are needed. By treating human, animal and ecosystem health as interdependent, One Health provides a framework for more effective prevention and for reducing the likelihood and impact of future pandemics.